SYDNEY coach John Longmire is in favour of changing the medical-sub rule, saying he has no qualms with it being either an extra interchange player or a sub that can be used at any time.

The medi-sub initiative has been brought into sharp focus this week after Richmond subbed out key position player Ben Miller in the dying stages of its draw with Fremantle on Friday night for the speedy Maurice Rioli jnr.

Miller showed no clear sign of injury and there were conflicting reasons provided post-game as to what his injury was.

Along with the Richmond controversy, there have been numerous incidents whereby a subbed out player has been fit enough to play the next week, which went against the initial guidelines for the rule's implementation.

Maurice Rioli jnr chases Hayden Young during Richmond's clash against Fremantle in round 19, 2022. Picture: AFL Photos

Longmire has no issue with the calls from many to open the sub up as a move that can be made at any time in a game.

"I think that should be considered. If you lost a player and only had four on the interchange that's too much of a disadvantage," he said.

"It wouldn't worry me if it was just a five (on the interchange) or a straight sub and you went back to that."

The Swans coach defended the medical substitute process, which was backed by the coaches ahead of its introduction at the start of last season. 

Josh Kennedy sits on the bench during the round 10 clash between Sydney and Carlton at Marvel Stadium on May 20, 2022. Picture: AFL Photos

"I think what it was brought in for, there was a sound rationale behind it. Take pressure off the doctors and look after the player's welfare," Longmire said.

And he's not overly concerned at this stage about the rule being manipulated in big games between now and the end of the season, including in finals.

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"Maybe, but let's not deal with too many hypotheticals," he said.

"I'd probably give the benefit of the doubt to the doctors and clubs to manage it. Majority of the time it's pretty good. A couple of times it might get a bit of air play.

"It's there for an injured player and a player that's been concussed, and those safety mechanisms are good for the players. Not everything is going to be perfect every game and we can jump up and down about a couple of things that jump out."